Units of Measure

1. Units of Measure Math for Clinical Practice

2. Weight • Kilogram = kg • Gram = g • Milligram = mg • Microgram = mcg

3. Length • 1 meter = m • Centimeter = cm • Millimeter = mm

4. Volume • 1 liter = L • 1 milliliter = mL or cc (cc is not to be used anymore according to JACOH standards but it is a common error since it has been used for years) CC = mL

5. Length • 1 meter (m) = 100 cm or 1000 mm • Centimeter (cm) = 10 mm • Millimeter (mm) = 0.1 cm

6. Household Abbreviations • 1 ounce or oz • Tablespoon = Tbs • Teaspoon = tsp or t

7. Conversion of Metric Units

8. Household Measurement • 1 ounce (oz) = 30 mL • 1 tablespoon (Tbs) = 15 mL • 1 teaspoon (tsp) = 5 mL

9. Ounces to mL • You are doing intake and output and the mother states the infant has consumed 3 ½ ounces of formula. How many mL has the infant consumed? • 3.5 x 30 mL = 105 mL • You would record 105 mL on the intake record

10. Measuring Liquids

11. Tablespoons • You are teaching a geriatric patient how to measure her medications. She is to take 15 mL of liquid Maalox to aid digestion. • You would instruct her to use what household measuring device to take her mediation? • Teaspoon or tablespoon • She would take one tablespoon of medication.

12. Teaspoon • You are working with a mother of a toddler and she has been instructed to give the child 1 ½ teaspoons of medication. You are demonstrating how to give the medication with a syringe with measurements in mL. • How many mL would you have her give?

13. 1 Teaspoon = 5 ml • 1 ½ teaspoons = 1.5 teaspoons • 1.5 teaspoon x 5 mL = 7.5 mL • You would have her draw up 7.5 mL in a po syringe.

14. Nursing Alert • Remember if there is not a number to the left of the decimal point a zero is placed there to highlight the decimal point placement. • Correct: 0.5 mL or 0.25 g • Incorrect: 5.0 mL or 25.0 g

15. Nursing Alert • Decide whether you are converting from smaller unit to larger unit or larger unit to smaller unit.

16. Liter to milliliters • 1 liter (L) = 1000 milliliters (mL) • 1.2 L = ___________ • 1.2 x 1000 = 1200 mL

17. Milliliters (mL) to Liters (L) • Change mL to Liter (L) • mL is smaller than a liter • Move decimal point three places to the right • 750 mL = 0.75 L

18. Metric Units Weight • Kilogram = kg • 1 kg = 1000 grams (g) • 1 gram (g) = 1000 milligrams (mg) • 1 milligram (mg) = 1000 micrograms mcg

19. How to calculate kilograms • Remember you will weigh less in kilograms • To convert pounds to kilogram you divide by 2.2 • Convert 100 pounds to kg • 100 / 2.2 = 45.454 or 45.45 • In the infant / small child carry out to the 100th or two decimal places.

20. Example • Convert the following metric measurement: • 0.2 mg = ______ g. • (gram is larger than a mg) • Need to move the decimal 3 places or divide by 1000. • Answer 0.2 mg = 0.0002 g

21. Example • 100 mcg = ______ mg • You are going from a smaller unit to a larger unit. • You would move the decimal point 3 places or divide by 1000. • 100 mcg = 0.1 mg

22. International and Milliequivalent Measures

23. International Units • Heparin, insulin, penicillin, epoetin products (Epogen, Procrit) are measured in international units. • Example: regular insulin 10 units SQ in am • Example: penicillin 600,000 units IM x one dose

24. Milliequivalent Measures • Do not confuse with milligrams. • Notation is mEq • Milliequivalent measures the number of grams of equivalent weight of a drug contained in 1 mL of normal saline.

25. mEq • Common drugs: sodium bicarbonate, sodium chloride, potassium chloride. • Examples: • 10 mEq of potassium chloride to ½ L of IV solution • 15 mEq of sodium chloride to 1 L of IV solution

26. Conversions

27. Conversions • Clinical connection: often you need to calculate between different systems of measure.

28. Metric System • Metric System • 1 kg = 1000 g • 1 g = 1000 mg • 1 mg = 1000 mcg • 1 L = 1000 mL

29. Grains 60 mg = 1 gr 45 mg = ¾ gr 30 mg = ½ gr 15 mg = ¼ gr 10 mg = 1/6 gr

30. Conversion to Metric Equivalents 60 mg gr1 45 mg gr 1/4 15 mg Gr 3/4 gr 1/2 30 mg

31. Practice Problems • gr ¾ = ___________ mg • gr ¼ = ___________ mg • gr 15 = ___________ mg • 300 mg = _________ gr • 60 mg = __________ gr • 30 mg = __________ gr • gr 1/6 = ___________ mg

32. Practice problems • The bottle of Tylenol states that you are to give X (ten grains) of Tylenol. • How many mgs are you giving ________

33. Chapter Review

34. Calculations in the Clinical Setting

35. Ratio – Proportion Method • Using the ratio proportion method offers a systematic approach to solving clinical math calculations.

36. The Set-up • Solving the unknown • The cookies and the eggs • If the recipe states you need 2 eggs to make 2 dozen cookies. How many eggs do you need to make a dozen cookies? • 24 cookies12 cookies • 2 eggs = x eggs

37. Practice Problem • Page 106 • Lorazepram 3 mg IV every 6 hours as needed. • Lorazepam is supplied as 4 mg / mL

38. The set-up • 4 mg3 mg • 1mL = x mL • (cross multiply) • 3 / 4 x = 0.75 mL • You would draw up 0.75 mL to equal 2 mg of Lorazepam

39. Practice Problem • Page 108 • Phenytoin sodium 300 mg by mouth at bedtime. • Phenytoin sodium supplied as 125 mg / 5 mL.

40. The Set-up • 125 mg300 mg 5 mL = x mL (Cross multiple) (X is on the bottom) 1500 125 X = 12 mL equals 300 mg of the drug

41. Practice Problems • Remember to label properly and put the x on the bottom.

42. Body Weight

43. Review • Pounds to kilograms • Pounds divided by 2.3 • Practice problems 1-10 page 140-41

44. Practice Problem • Neupogen 5 mcg/kg/day IV over 30 minutes. • Patient weight = 174

45. Change Pounds to Kilograms • 174 / 2.2 = 79.09 kg

46. Determine the dosage • 5 mcg / kg / day • 5 mcg x 79.09 (weight in kg) = 395.45 mcg per dose • Drug is rounded to 395 mcg per dose to be added to 50 mL of Dextrose 5% in Water.

47. Practice Problem • Phenobarbital 30 – 120 mg / kg per day in 3 divided doses • Physician orders the maximum dose or 120 mg / day to be given q 8 hours. • 1st you would need to divide 120 mg by 3 doses = 40 mg per dose

48. Determine the Amount • Phenobarbital is provided as 65 mg / mL • For one dose you would need to draw up how much of the medication? • 40 mg = 60 mg x mL 1 mL 40 mg = 0.66 mL 60 x